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  1. #1
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    Dahon - Fork Replacement for 100 mm hub?

    I have a late-model Boardwalk that I would like to convert to hub brakes (not disc brakes) for 4-season commuting.

    Prior to purchasing this Boardwalk, I had been using hub brakes (i.e., drum, roller, and disc) exclusively for a few years on various commuter bikes. When the summer drought finally broke in mid-October, and I found myself commuting in the rain on my "V-brake" equipped Boardwalk, I rediscovered the limitations of rim caliper brakes and began thinking of how to mount roller brake-equipped wheels on the Boardwalk.

    For those who don't know, "roller brakes" are a cable-operated hub brake manufactured by Shimano for use with its Nexus and Nexave lines of hubs. While they are a bit heavy, I have found them to be an excellent brake for everyday, all-weather commuting (low cost, low risk of theft, low maintenace, quiet, very reliable).

    The catch is that the Nexus/Nexave front hub is of a standard, 100 mm OLN design and the Dahon fork uses the narrower 74 mm OLN dimension.

    I'm not a big fan of the straight fork on the Boardwalk and would be happy to replace it with a traditional curved fork. Specifically, I would need a 20 in. curved fork with:

    - 100 mm drop out width
    - 1 1/8 in. threaded steerer tube (for use with threaded Dahon headset & 1 1/8 in. handlepost)

    Ideally, the fork would be ChroMoly and would not have cantilever studs, but I'm not picky on these two points.

    Does anyone know where to order such a fork? I have seen lots of threadless 1 1/8 in. forks and a couple of threaded 1 in. forks, but have not seen any threaded 1 1/8 in. forks.

    As an alternative, does anyone have any experience converting a Dahon to a threadless fork and headset? If so, how do you keep the headset adjusted properly? Does it work well with the handlepost?

    Any ideas would be appreciated. Thanks.

  2. #2
    Señor Mambo
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    How about spreading the current forks to 100mm? (Many LBSes will do this if you just bring in the bare fork. If you bring the whole bike in, they might not want to do it because of warranty issues. I've spread forks before using a 2x4 and copper pipe. )

    The only other issues would be whether you significantly alter its folded state - i.e. whether it would stay folded - and/or whether the spread forks still fit 20" wheels.

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    I am not concerned about the effect of this change on folding the bike. My routine does not require me to fold the bike and I bought it for other reasons (e.g., low step-over, short LOA, small wheels, low carrier rack height).

    I am, however, a little nervous about spreading the fork from 74 to 100mm. 10 or 15mm seems doable, but 26mm sees like a stretch, to use an expression .... The Dahon fork looks lightly built. I'm sure that it's strong and would probably hold up, but a lot is at stake ....

    The other consideration is the resulting profile of the fork blades and how they will relate to the shape of the Nexus or Nexave hub (I have both models of hub available to me) and the attached roller brake. Hub brake wheels don't fit into every fork or frame, and much depends on dropout shape and the angle of the fork blades or chain/seat stays. I'm not saying that it won't work, but I'd want to take some measurements and make some scale drawings before getting out the crowbar ...

    Are you aware of Bike Forum members or others who have spread Dahon forks to 100mm?

    Thanks.

  4. #4
    New usename ThorUSA brakemeister's Avatar
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    I would strongly urge not to bend the fork ..... that will result in disaster.
    Check on the dahon website ,,, they have a swiss distributor who makes hoped up Dahons with his own forks 100 mm wide.
    Or try a Magura hydraulic rim brake , they work very nice and are much more constant than V brakes in wet weather. Not more powerful, just more constant throughout all kinds of weather

    Thor

  5. #5
    Señor Mambo
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    Quote Originally Posted by ETRTO 520
    Are you aware of Bike Forum members or others who have spread Dahon forks to 100mm?

    Thanks.
    Sorry, no. I agree with brakemeister and you that I would not want to spread these forks 26mm, but I am not aware of any off-the-shelf solutions for a 1 1/8" threaded fork for 20" wheels, except for the RANS recumbent LWB fork, but this fork is alloy and has tremendous rake - plus I think the head tube is too long anyway (though I know nothing about Dahon stems or dimensions in general).

    If that solution does not work out, you can always talk to to J at Gaerlan since he makes folding bikes and knows Dahon's pretty well; in fact he might be able to custom manufacture a cromoly fork for you. Otherwise it wouldn't hurt to ask the guys at CAT, or go with that Swiss distributor. Or you can buy your own fork and tap and die set and thread it yourself. Fun!

  6. #6
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    Thanks to Spambait11 and Brakemeister for your suggestions.

    Prior to posting this thread, I looked that the Gaerlan web site. He has a couple of nice 20 in. forks available but they have 1 in. steerers, not 1 1/8 in.

    The RANS fork is a good idea. I did not come across it while searching the first time, so thanks for the link. The fact that it is aluminum is a little intimidating, but I'm open to the idea if I can get assurances regarding strength. Again, assuming it's strong enough, the rake does not bother me: indeed, I prefer it. Finally, since it is alloy, it should not be too hard to cut additional threads, assuming I can find the right 1 1/8 in./25 mm die.

    I couldn't find the 100mm fork on the Dahon web site. I looked in Accessories and on the Swiss distributor's web site (in German ...).

    But how about the idea of a threadless 1 1/8 in. fork? There are quire a few 20 in. forks available in the threadless format (although will admit that most of them are chunky BMX forks that don't interest me).

    My bike shop professional experience pre-dates threadless headsets by about 5 or 10 years, and the two bikes that I have with threadless headsets ... well, let's just say I have never quite got the trick of adjusting them. Moreover, I don't even know the terminology.

    My experience with threadless headsets is that the stem acts as the lock nut. Of course, there is no stem on a Dahon, and I don't fancy the thought of trying keep a headset adjusted by somehow fine-tuning the Dahon handlepost.

    On the other hand, if someone makes a threadless headset with one or more (lateral) set screws on the top races, it would be theoretically possible to assemble the headset and adjust the fork, then attach the handlepost.

    Any further thoughts? Thanks again.

  7. #7
    Señor Mambo
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    Quote Originally Posted by ETRTO 520
    On the other hand, if someone makes a threadless headset with one or more (lateral) set screws on the top races, it would be theoretically possible to assemble the headset and adjust the fork, then attach the handlepost.
    Hmm...
    Don't know if you saw this while cruising the RANS site, but this article talks about a handlebar modification with a threadless headset. Not only that, but they sell the components you need to make this modification. I assume that once you're able to lock the forks into the head tube then setting the handlebar stem is pretty straightforward? In any case, I think the clamp they use in the article matches what you're describing as "(lateral) set screws"?

    Another thought might be to use the Diatech headset with a head tube reducer as posted here on Gaerlan's site to reduce the head tube diameter from 1 1/8" to 1" - then you can use a threaded 1" fork. Unless, of course, the Dahon stem won't fit...
    But if folding is not a priority to you, maybe you can just make your own handlebar stem/post?

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    Thanks, spambait11.

    The referenced article does inspire! The only problem is that the clamp that he uses to secure the headset is not quite what I had in mind ... still, it does give me some ideas. What I had in mind was some sort of headset that had built-in set screws that would press against the fork's steerer tube, thus eliminating the need for a separate clamp.

    The catch here is that I want to avoid too much stack height on the upper part of the headset. Right now I have a budget, non-adjustable Dahon handlepost (the "Revolve" (???)) that is chopped off at the top (with a pipe cutter ...). To attach the stem (and the drop handlebar), I inserted a 1 1/8 in. quill aheadset adapter. For reasons not worth mentioning here, I can't chop off any more of the handlepost.

    But the fact that a separate clamp is needed does not need to be a problem. The clamp that is used in the article is a good 1.5 to 2 in. high, with two clamp bolts. For my application, I think that it could be replaced with a simple seat clamp, which could be 1/2 in. high or shorter.

    Worst case, if I need to use a wide clamp and, as a result, the stack height is too high, I can buy an adjustable Dahon handlepost. That way, I don't need to worry about stack height, because I can adjust the stem downward, thus ending up with the same handlebar height.

    The next challenge is to find a 20 in. chromoly fork with 1 1/8 in. threadless steerer that is not a BMX fork !

  9. #9
    Senior Member Dave Hickey's Avatar
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    How about a headset reducer? Pricepoint has them for $10.00. It allows you to use a 1 1/8 headtube with a 1" fork and headset

    http://www.pricepoint.com/detail/118...t-Reducer-.htm

  10. #10
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    Thanks for the suggestion. The problem is that newer Dahons like mine use a handlepost with a 1 1/8 in. quill that, of course, requires a 1 1/8 in. (25.4 mm I.D.) steerer tube (the "handlepost" is the riser that goes from the top of the fork's steerer tube up to the stem or handlebar: depending the model and how it's adjusted, it can be about 16 in. high).

    Older Dahons use a 1 in. (22.2 mm I.D.) handlepost, but people complain about them as being too flexible. I haven't used one, but my general feeling on the matter is that when you have such a long riser, you want as large a diameter as possible. Therefore, I'm not inclined to go back to the 1 in. fork. On the other hand, that would solve my fork problem ....

  11. #11
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    Two days ago, I wrote to RANS' e-mail address for bicycles (as opposed to aviation), asking whether the RANS aluminum 20 in. fork would work on (i.e., be stoung enough for) a conventional bike. I have not heard back.

    But, in any case, my first choice for a replacement fork would be high-quality steel, not aluminum or exotics.

    So, does anyone know of a source for a 20 in., curved (non-BMX), chromoly replacement fork with a 1 1/8 in. threadless steerer ? ....

  12. #12
    New usename ThorUSA brakemeister's Avatar
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    I can tell you why rans is not answering

    its called product liability

    they cant tell you that the fork is working , as they do not have the whole product in their hands ... i.e. its going on a different bike

    they cannot tell you its NOT working
    cause some lawyer might acrue out of that answer that the fork is not strong enough

    way back my former boss told me that they are 80 ways to screw up a fork ( when built from scratch ) and although I am sure he overstressed it just a little bit, the bicycle fork is not something to play around with easily

    thor

  13. #13
    Señor Mambo
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    Quote Originally Posted by ETRTO 520
    So, does anyone know of a source for a 20 in., curved (non-BMX), chromoly replacement fork with a 1 1/8 in. threadless steerer ? ....
    Maybe eBay perhaps? I know a lot of recumbent riders often upgrade their cromo forks for bouncy ones and will often sell their old forks. Haven't seen any listed for a while though. You could also try to place a want ad at hostelshoppe.com and bentrideronline.com.

    Also, Gaerlan sells the Dahon handle bar stems that will fit 1" head tubes. Maybe it's easier getting one of these stems plus a head tube reducer and a 1" threaded/less cromo fork. Can you adapt your current handlebar setup?

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    Again, thanks to Brakemeister and spambait11 for your respective thoughts and observations.

    The RANS people did just get back to me (a couple of minutes ago) and it is more or less what Brakemeister suggested: "Not able to answer that ..."

    I am unconcerned, since, in the past couple of days it's become clear to me that I don't want an aluminum fork .... even it it's the perfect fit ...

    The recumbent idea is a good one. Yesterday, I actually added a thread re: 20 in. forks on the recumbent section of Bike Forums, so we'll see where it goes. It seems to me that that there should be plenty of 20 in. forks in the recumbent world. Whether they have 1 1/8 in. steerers is another question.

    Finally, I have to decide, as per spambait11's suggestion, whether my desire for hub brakes justifies going to a 1 in. fork and, therefore, a matching 1 in. Dahon handlepost. It certainly would be the fastest way to achieve the conversion, but it would mean giving up whatever advantage the beefier Dahon handlepost has (I'm not sure it has one, but it would stand to figure that bigger is better in this application), plus the following costs:

    - Replacement fork: $34
    - Replacement handlepost: $38
    - Headtube reducers: $29

    (all of the above from Gaerlan)

    Would it not be so much easier - and cheaper - if someone made a 20 in. X 1 1/8 in. road fork !!!!

  15. #15
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    Dear ETRTO 520,

    This matter of drum brakes being fitted to Dahon folding bikes has had extensive discussion on the Dahon Community Forum earlier this year - to which both Brakemeister and I have contributed several posts - though with rather different opinions about the usefulness of drum brakes.

    Like you, I have experienced the limitations of rim brakes in the very wet and muddy conditions that we often have on the canal towpaths and cycle trails in the Glasgow area, and also on the hilly terrain and steep slopes that we have locally. After trying various models of V-brakes on my Phillips Boardwalk Lite (an older model of the Dahon Helios) and experiencing no real improvement, I also opted for sealed drum brakes.

    So I had two new wheels equipped with drum brakes built by our local bike shop (Kinetics). The front wheel has a SRAM Spectro drum brake. The back wheel is fitted with a Shimano Nexave roller drum brake. Both brakes are operated using the existing brake levers that were already fitted on the bike. They give excellent stopping power - as good as the V-brakes were in the dry and much better than the V-brakes in the wet.

    You then asked the question - "Are you aware of Bike Forum members or others who have spread Dahon forks to 100mm". Well the answer is that this is exactly what Ben Cooper at Kinetics did in order to fit the new front wheel with its hub brake to my Boardwalk Lite. When I asked him about this particular matter, he told me he does this spreading from 75mm to 100mm using a special tool that is built for the purpose. Apparently he has performed this task on quite a number of occasions. He also told me that, as long as it is a steel fork with TIG welding that is being spread (as is the case with the Boardwalk Lite), there is no difficulty in carrying out the operation successfully. The steel is sufficiently ductile to allow the spreading to be done relatively easily. However he told me that he would not attempt to do this spreading operation with an aluminium fork or with any fork having braised fork tubes.

    Since it wasn't me who carried out the actual work, if you do wish to get more detailed information about the spreading of the forks, I suggest that you send an e-mail message to Ben Cooper at the following address - mail@kinetics-online.co.uk

    Details of the SRAM Spectro drum brake are given on the hubs and headsets pages of the Kinetics Web site with the following URLs:- http://www.kinetics.org.uk/html/hubs___headsets.shtml
    http://www.kinetics.org.uk/html/hub_brakes.shtml

    I hope that this information is useful to you.

    Gordon Petrie

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    Thank you, Gordon, for such a detailed reply. I'm sorry I missed the earlier postings, as it would have saved you some typing time! I did search on several key words before posting this thread, but didn't turn up the earlier discussion.

    You do not need to convince me of the usefulness of hub brakes. Prior to acquiring the Dahon Boardwalk in June of this year, I rode a roller brake-equipped cycle for about two years. It was a commuting bike that I assembled on a 6-speed Specialized BMX frame. As I stand only 5 ft. 7 in. (170 cm), it seemed that, by using a very long (16 in./40 cm) seat pillar and a long, steel stem extender, I could manage to make this small frame rideable. Since the fork spacing was standard, I was able to equip the bike with front and rear roller brakes on 20 in. (ETRTO 406) wheels.

    I discovered over time, however, that I was a hair too tall for the bike. If I were an inch or two shorter, I'd still be riding that bike, as it served me well. The Dahon was intended as a replacement (of course, the Dahon was too big, but that's another story ...).

    What I did not know when I bought the bike was that Dahon used the 74 mm OLN standard for its forks. The bike's stock brakes did not pose a problem this summer when the New York region suffered a long summer drought, but when the rains returned in earnest in October, I rediscovered, in a rather frightening way at times, the limitations of caliper brakes, even the efficient "linear pull" type.

    I was not able to check this thread over the weekend. In that time, I came across a 1 1/8 in. BMX-style chromoly fork (with, most unusually, slightly curved fork blades) that was being offered at an on-line auction site. As there were no other bidders, I was able to secure it for a small sum, inclusive of shipping. In the first instance, since I have committed to buy and, in fact, have paid for the fork, I will go ahead and install it after I have built up a new pair of wheels based on my existing set of roller brake hubs and new rims.

    I suspect that the new fork may result in a harsher ride (and a heavier bike!!!), as it looks quite a bit more robust than the stock Dahon fork. If need be, I will install 20 x 2.0 in. tires to add a bit more cushion (replacing the nominal 1.75 in. but somewhat narrow Haro tires that I have been running).

    In any event, I am encouraged to learn, however, that the steel "unicrown" Dahon forks can be "cold set" (i.e., intentionally bent), if need be. By the way, do you have a sense of the weight of the riders who have had their Dahon forks spread to 100 mm? Would that affect the decision to cold set the fork? (I weigh in at a stocky 170 lbs. (12+ stone)).

    Last but not least, does anyone have any experience with the much-hyped Schwalbe "Big Apple" tires? Would 20 x 2.0 Big Apples soften the ride? Do they roll reasonably well? Can anyone suggest a fast-running 20 x 2.0 in. tire, or a generously proportioned 1.75 in.?

    Thanks.

  17. #17
    Neat - w/ ice on the side dalmore's Avatar
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    You might check out Worksman bicycles. They make a folding bike with 20-inch wheels and apparently a front drum brake option if I am reading the price list correctly. Could be a source for the parts you need. Or not - <shrugging> - worth an email I would think.
    Last edited by dalmore; 11-01-05 at 12:03 AM.

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    Well, the BMX fork arrived today. It's really quite well made. And it look's great too. But I don't think I'll be using it!

    First of all, it weights a ton (well, 3.5 lbs. ...). Second, and more importantly, although the O.D. of the steerer is clearly the standard 1 1/8 in., the steerer tube is very robust so its I.D. is not 1 in. (25.4 mm). It looks more like 7/8 in. (approx. 22 mm). That means that the Dahon handlepost won't fit.

    Looks like I may need to break out the crowbar after all !!!

  19. #19
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    Dear ETRTO 520

    In answer to the various points made in your messages, the Boardwalk Lite (nee Helios) has a traditional fork that is curved forward rather than the straight fork that you have on your Boardwalk. The fork tubes are bent inwards at the top.

    I do hope that you can find the correct tool with its controlled spreading mechanism rather than having to resort to the crowbar(!) or the use of wooden blocks being hammered down to spread the forks.

    I don't have any information about the weight of the other riders who have had the forks of their Dahons spread. In my own case, I am 5ft. 9in. tall and weigh 178 lbs.

    Regarding your query about tyres, I found that the semi-slick tyres that were fitted originally to the Boardwalk Lite and to my wife's Giant Halfway had little or no grip on our rough cycle paths and towpaths in wet or frosty weather and punctured with distressing frequency - one every other week. So we changed to Impac 20 x 1.75 BMX tyres on both bikes. These give much more grip and also a softer ride. Besides which, the number of punctures has been greatly reduced - two on the Halfway and one on the Boardwalk Lite over a period of two and a half years - with continuous use of the two bikes.

    At the time of the BMX tyres being fitted, the Big Apple tyres were not on the market. However, in March of this year, during a visit to Boston, I bought a Helios P8 (at a saving of $300 over the U.K. price!) and shipped it back home as accompanied baggage. The semi-slick tyres fitted on the Helios were again quite unsuitable for our conditions. So I did consider fitting the Big Apples as replacement tyres. However I was put off doing so by the discussions on the Dahon Forum which indicated that, if the Big Apples were fitted, then there was insufficient room to fit mudguards (fenders) - which are essential in our weather conditions. So I fitted Marathon Plus tyres in conjunction with the Dahon special edition SKS P45 mudguards which provided just enough clearance. These tyres give a reasonable grip but have a much firmer ride than the BMX tyres. So far, they have lived up to their reputation as being highly puncture resistant.

    Gordon Petrie

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    Again, thanks Gordon for the detailed reply.

    No need to worry about the crowbar ! I worked in a cycle shop once upon a time and, in the intervening years, have managed to assemble a collection of specialized shop tools, including, believe it or nor, a fork truing jig and the truing lever itself. The jig holds the fork and the attached gauges allows the user to confirm that the two blades are being trued or cold-set in a symmetrical manner.

    Although I would love to have roller brake-equipped wheels on the Boardwalk as soon as possible, realistically speaking, it may be several weeks before things come together.

    I will start by measuring the Boardwalk's fork in its current state so that I can determine that the Nexus/Nexave roller brake hub would fit if the fork were cold-set to 100 mm. That's not a given, but I am optimistic that it will fit. The trick will be to line up the brake counterforce arm with the fork blade in such a way that the arm parallels the blade without hitting it.

    If it looks feasible, I will order a pair of rims and build the roller brake-equipped wheels. Only then will I put the fork in the jig ...

    Thanks for your advice regarding the Big Apple tires. I have nominal 1.75 in. (but somewhat narrow) Haro tires on the Boardwalk, and there is a fair amount of clearance under the mud guards. It makes me think that the Big Apples might fit, albeit closely (it could be that the Helios, a faster bike, is designed with less clearance). I may put this question to J. Gaerlan, a Dahon (and other bike) expert who maintains a shop in California, as I will be purchasing the rims from him.

    However, if I stick with the original Dahon fork (cold-set to 100 mm), I might not need the wider tires. The wide tire idea grew out of my earlier plan to replace the Dahon fork with a rigid BMX fork.

    Thanks again,

    Tony

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    Stefan Stiletto
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    Hi ERTO,

    This is exactly what I want to do to a Dahon Speed D7. I know it is three years later but please could you give us an update and let us know how it went.

    cheers

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    Also interested.

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    Dahon_Roo_Controller.jpgDahon%20Gabel%20Umbau2.jpgUmbau%20Dahon%20Stahl-Gabel.jpgStarrgabel.jpgConversion to 100 mm wide fork works (Dec. 2009).
    You don’t get a 100 mm wide fork from VeloWerk in Schaffhausen Switzerland, unless you go there personally and pay cash :-).

    I converted two Dahon bikes (Ciao D7 and Roo D7) to front motor driven electrical bikes. The front motor is 100 mm in width. The fork was replaced by commercial forks with 1” steering shaft, details see below.
    Dahon Roo D7, image 1, adapted from here:
    http://www.pedelecforum.de/forum/showpost.php?p=49665&postcount=218

    Fork conversion:
    I widened the inner diameter of the Dahon forks steering tube to 1 inch + 0,05 mm with a lathing machine

    and put the new steering tube of the 1 inch fork, image 4 above, into the steering tube of the dahon fork, image 3 above shows the (truncated) Dahon fork at the right.

    The 2. image above shows the Dahon steering tube on top of a 1" fork (in this case the 1" fork is grey in color) just before it is inserted into the Dahon frame.

    Text in poor english is also to be found here:
    http://www.pedelecforum.de/forum/showpost.php?p=46126&postcount=175


    Finally I used the red fork to be seen in image 4.. I bought it as "2. choice" because of scratches on the surface, price 10€, sold at ebay Germany, search keywords: Starrgabel, or: KLAPPRAD 20"

    technical data (translated/in German)
    length of steering tube: Schaftlänge mit Gewinde ca. 19 cm
    total heigth: Gesamtlänge ca. 53 cm
    diameter of steering tube: Schaftdurchmesser von ca. 25,5 mm
    hub(?) width at wheel axis: Innenbreite ca. 10 cm
    brakes: Bremsaufnahme V-Brake
    max. heigth of wheel: Innenhöhe ca. 29 cm

    I guess the following forks are also suited:
    prism fork:
    http://www.bikestore.cc/product_info.php/products_id/12594.html
    and:
    http://alles-fuer-das-rad.de/popup_i...866c45b70cc65d
    Attached Images Attached Images
    Last edited by Schwipp; 12-02-09 at 09:13 AM.

  24. #24
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    Ahead_Kralle.jpg
    last image:
    Here you see a look at the commercial Ahead Clamp for 1" steering tubes which I also had to use.
    Last edited by Schwipp; 12-02-09 at 09:11 AM.

  25. #25
    Senior Member kamtsa's Avatar
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    Quote Originally Posted by ETRTO 520 View Post
    ...When the summer drought finally broke in mid-October, and I found myself commuting in the rain on my "V-brake" equipped Boardwalk, I rediscovered the limitations of rim caliper brakes ..
    Have you considered replacing the brake pads? For example, the Koolstop Salmons are said to brake very well in wet conditions.

    Kam

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